1. Field of the Invention
This invention relates, in general, to gun sights for shotguns and other firearms. More specifically, this invention relates to an adjustable sighting system that may be used for sighting-in a plurality of shooting tasks, for example, shooting with different ammunition, such as long range and close range ammunition.
2. Related Art
For hunters, sportsmen, law enforcement personnel and other gun users, it is difficult or impractical to carry several firearms in the field. However, the type of ammunition used is often changed in response to the demands of different situations, for example, the change from large to small game. Consequently, a number of smoothbore firearms, and their ammunition, have been modified to improve their effectiveness over a range of shooting tasks. One such modification permits the firing of a plurality of ammunition from the same gun, for example, single-slug and buckshot loads. Typically, single-slug loads are used for long range targets, and buckshot loads are used for short range targets. Due to the substantially different ballistic characteristics of these loads, “zeroing-in” or “sighting-in” targets with these different loads using a single sight can be problematic.
Several attempts have been made to provide a shotgun sight that is capable of accurately sighting-in shots taken with both slug and buckshot loads. For example, U.S. Pat. No. 2,781,583 (Grumble) describes a gun sight attachment, which converts the typical bead sight of a shotgun to a blade sight, such as may be found on a rifle. The blade sight attachment slides over the tip of the barrel and surrounds the bead sight and barrel tip.
U.S. Pat. No. 3,193,932 (Johnson) discloses a detachable front sight that may be used to assist in the sighting of a gun when firing different ammunition. This sight extends vertically above the gun barrel at its tip and replaces the normal bead sight. Screws are threaded through the generally flat upper surface of the sight and into the barrel to hold it in place.
U.S. Pat. No. 3,975,851 (Bedford) teaches another detachable sight for use with shotguns that helps users align slug-load shots with a target. This sight comprises a rear-mounted apparatus featuring a V-shaped notch through which the front sight, typically a bead sight, may be viewed. In one embodiment of this design, adjustments for windage and elevation may be made.
Some firearms of the late 1800's and early 1900's included a rear sight device featuring range adjustability for a single ammunition. A Model 1898 U.S. Magazine Rifle includes a sighting device having an elongated “leaf” with indicia to provide a calibration reference for range. The eye piece of this sighting device is raised or lowered to achieve increased shooting accuracy at a desired range, by means of a slide that is moved along the leaf to the appropriate indicia. Still, this 1898 sighting device has a single rear sight, that is, a single “zero.” This 1898 device has one elevation adjustment and one windage adjustment. It is adapted for use with a single firearm shooting a single ammunition over a range reportedly from about 200–2000 yards. Such a sight is understandable in view of the state of the art in such firearms of that era, wherein the military firearm and ammunition may have produced a trajectory that required substantial adjustments in aiming, especially in elevation, depending on distance of the target from the user of the firearm.
Another firearm of the late 1800's included a rear sighting device featuring range adjustability for a single ammunition. A Model 1899 military rifle includes a rear sighting device with a pivotal arm. The pivotal arm carries a single member that has two outer surfaces that may each be used as a sight. Pivoting the arm serves to place one or the other of the outer surfaces in a position for use as the rear sight. The 1899 sighting device does not have two separate sighting members and does not have separate elevation adjustment for a plurality of sights and does not have separate windage adjustment for a plurality of sights. Again, such a sight is understandable in view of the state of the art in such firearms of that era, for making substantial adjustments in elevation.
Still, there remains a need for a sight system that may be used to accurately sight-in or “zero” shots with various ammunition (such as slugs or buckshot), or for varying shooting tasks as desired. There still remains a need for such a sigh system that does not require significant or difficult adjustments to the firearm in the field to switch sights for different ammunition.